Schema of study: Subcutaneous injection of 240 µg/kg of Plerixafor (Mozobil ®, Genzyme) at 8 am the day of the cytapheresis. Determination of CD34+ cells circulating in h0 then every hour of h3 to h11. Taking by cytapheresis from the 5th hour of the injection if the rate of CD34+ is upper or equal in 10.106/l. If the rate of CD34+ in the blood does not reach 10.106/l after the first injection of plerixafor or if the first cytapheresis does not allow the collection of at least 5.106/kg CD34+ cells, the patient will be considered in failure and a conventional mobilization by G-CSF(Granulocyte colony-stimulating factor) will be programmed.